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    <meta charset="UTF-8">
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    <title>Document</title>
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    <script>
        var a = 10;
        var b = 20;
        // 将a和b交换

        var temp = b;
        b = a;
        a = temp;
        console.log(a,b);

        // 先用temp将b值保存起来,然后将a赋值给b,然后将保存过的b赋值给a
    </script>
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